When forcing my laptop to swap, I almost immediately got the following firmware error. I'm not sure whether this is expected. Restarting the interface brought things back to normal.
dmesg follows. Feb 5 01:19:04 thinkpad /bsd: iwn0: fatal firmware error Feb 5 01:19:04 thinkpad /bsd: firmware error log: Feb 5 01:19:04 thinkpad /bsd: error type = "NMI_INTERRUPT_WDG" (0x00000004) Feb 5 01:19:04 thinkpad /bsd: program counter = 0x000006B4 Feb 5 01:19:04 thinkpad /bsd: source line = 0x0000D3EA Feb 5 01:19:04 thinkpad /bsd: error data = 0x0000000202630000 Feb 5 01:19:04 thinkpad /bsd: branch link = 0x0000067A0000071A Feb 5 01:19:04 thinkpad /bsd: interrupt link = 0x000015320000E762 Feb 5 01:19:04 thinkpad /bsd: time = 1346051188 Feb 5 01:19:04 thinkpad /bsd: driver status: Feb 5 01:19:04 thinkpad /bsd: tx ring 0: qid=0 cur=188 queued=135 Feb 5 01:19:04 thinkpad /bsd: tx ring 1: qid=1 cur=0 queued=0 Feb 5 01:19:04 thinkpad /bsd: tx ring 2: qid=2 cur=0 queued=0 Feb 5 01:19:04 thinkpad /bsd: tx ring 3: qid=3 cur=0 queued=0 Feb 5 01:19:04 thinkpad /bsd: tx ring 4: qid=4 cur=135 queued=0 Feb 5 01:19:04 thinkpad /bsd: tx ring 5: qid=5 cur=0 queued=0 Feb 5 01:19:04 thinkpad /bsd: tx ring 6: qid=6 cur=0 queued=0 Feb 5 01:19:04 thinkpad /bsd: tx ring 7: qid=7 cur=0 queued=0 Feb 5 01:19:04 thinkpad /bsd: tx ring 8: qid=8 cur=0 queued=0 Feb 5 01:19:04 thinkpad /bsd: tx ring 9: qid=9 cur=0 queued=0 Feb 5 01:19:04 thinkpad /bsd: tx ring 10: qid=10 cur=0 queued=0 Feb 5 01:19:04 thinkpad /bsd: tx ring 11: qid=11 cur=0 queued=0 Feb 5 01:19:04 thinkpad /bsd: tx ring 12: qid=12 cur=0 queued=0 Feb 5 01:19:04 thinkpad /bsd: tx ring 13: qid=13 cur=0 queued=0 Feb 5 01:19:04 thinkpad /bsd: tx ring 14: qid=14 cur=0 queued=0 Feb 5 01:19:04 thinkpad /bsd: tx ring 15: qid=15 cur=0 queued=0 Feb 5 01:19:04 thinkpad /bsd: tx ring 16: qid=16 cur=0 queued=0 Feb 5 01:19:05 thinkpad /bsd: tx ring 17: qid=17 cur=0 queued=0 Feb 5 01:19:06 thinkpad /bsd: tx ring 18: qid=18 cur=0 queued=0 Feb 5 01:19:06 thinkpad /bsd: tx ring 19: qid=19 cur=0 queued=0 Feb 5 01:19:06 thinkpad /bsd: rx ring: cur=47 Feb 5 01:19:06 thinkpad /bsd: 802.11 state 4 OpenBSD 5.9 (GENERIC.MP) #0: Fri Feb 5 00:38:43 EST 2016 mike@thinkpad:/usr/src/sys/arch/amd64/compile/GENERIC.MP real mem = 4062691328 (3874MB) avail mem = 3933769728 (3751MB) mpath0 at root scsibus0 at mpath0: 256 targets mainbus0 at root bios0 at mainbus0: SMBIOS rev. 2.6 @ 0xe0010 (78 entries) bios0: vendor LENOVO version "6QET61WW (1.31 )" date 10/26/2010 bios0: LENOVO 3626FAU acpi0 at bios0: rev 2 acpi0: sleep states S0 S3 S4 S5 acpi0: tables DSDT FACP SSDT ECDT APIC MCFG HPET ASF! SLIC BOOT SSDT TCPA SSDT SSDT SSDT acpi0: wakeup devices LID_(S3) SLPB(S3) IGBE(S4) EXP1(S4) EXP2(S4) EXP3(S4) EXP4(S4) EXP5(S4) EHC1(S3) EHC2(S3) HDEF(S4) acpitimer0 at acpi0: 3579545 Hz, 24 bits acpiec0 at acpi0 acpimadt0 at acpi0 addr 0xfee00000: PC-AT compat cpu0 at mainbus0: apid 0 (boot processor) cpu0: Intel(R) Core(TM) i5 CPU M 540 @ 2.53GHz, 2793.51 MHz cpu0: FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE,SSE3,PCLMUL,DTES64,MWAIT,DS-CPL,VMX,SMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,POPCNT,AES,NXE,LONG,LAHF,PERF,ITSC,SENSOR,ARAT cpu0: 256KB 64b/line 8-way L2 cache cpu0: smt 0, core 0, package 0 mtrr: Pentium Pro MTRR support, 8 var ranges, 88 fixed ranges cpu0: apic clock running at 132MHz cpu0: mwait min=64, max=64, C-substates=0.2.1.1, IBE cpu1 at mainbus0: apid 1 (application processor) cpu1: Intel(R) Core(TM) i5 CPU M 540 @ 2.53GHz, 2793.00 MHz cpu1: FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE,SSE3,PCLMUL,DTES64,MWAIT,DS-CPL,VMX,SMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,POPCNT,AES,NXE,LONG,LAHF,PERF,ITSC,SENSOR,ARAT cpu1: 256KB 64b/line 8-way L2 cache cpu1: smt 1, core 0, package 0 cpu2 at mainbus0: apid 4 (application processor) cpu2: Intel(R) Core(TM) i5 CPU M 540 @ 2.53GHz, 2793.00 MHz cpu2: FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE,SSE3,PCLMUL,DTES64,MWAIT,DS-CPL,VMX,SMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,POPCNT,AES,NXE,LONG,LAHF,PERF,ITSC,SENSOR,ARAT cpu2: 256KB 64b/line 8-way L2 cache cpu2: smt 0, core 2, package 0 cpu3 at mainbus0: apid 5 (application processor) cpu3: Intel(R) Core(TM) i5 CPU M 540 @ 2.53GHz, 2793.00 MHz cpu3: FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE,SSE3,PCLMUL,DTES64,MWAIT,DS-CPL,VMX,SMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,POPCNT,AES,NXE,LONG,LAHF,PERF,ITSC,SENSOR,ARAT cpu3: 256KB 64b/line 8-way L2 cache cpu3: smt 1, core 2, package 0 ioapic0 at mainbus0: apid 1 pa 0xfec00000, version 20, 24 pins ioapic0: misconfigured as apic 2, remapped to apid 1 acpimcfg0 at acpi0 addr 0xe0000000, bus 0-255 acpihpet0 at acpi0: 14318179 Hz acpiprt0 at acpi0: bus 0 (PCI0) acpiprt1 at acpi0: bus -1 (PEG_) acpiprt2 at acpi0: bus 13 (EXP1) acpiprt3 at acpi0: bus -1 (EXP2) acpiprt4 at acpi0: bus -1 (EXP3) acpiprt5 at acpi0: bus 5 (EXP4) acpiprt6 at acpi0: bus 2 (EXP5) acpicpu0 at acpi0: C3(350@245 mwait.3@0x20), C2(500@205 mwait.3@0x10), C1(1000@3 mwait.1), PSS acpicpu1 at acpi0: C3(350@245 mwait.3@0x20), C2(500@205 mwait.3@0x10), C1(1000@3 mwait.1), PSS acpicpu2 at acpi0: C3(350@245 mwait.3@0x20), C2(500@205 mwait.3@0x10), C1(1000@3 mwait.1), PSS acpicpu3 at acpi0: C3(350@245 mwait.3@0x20), C2(500@205 mwait.3@0x10), C1(1000@3 mwait.1), PSS acpipwrres0 at acpi0: PUBS, resource for EHC1, EHC2 acpitz0 at acpi0: critical temperature is 100 degC acpibtn0 at acpi0: LID_ acpibtn1 at acpi0: SLPB acpibat0 at acpi0: BAT0 model "45N1170" serial 657 type LION oem "SANYO" acpibat1 at acpi0: BAT1 not present acpiac0 at acpi0: AC unit online acpithinkpad0 at acpi0 acpidock0 at acpi0: GDCK not docked (0) cpu0: Enhanced SpeedStep 2793 MHz: speeds: 2534, 2533, 2399, 2266, 2133, 1999, 1866, 1733, 1599, 1466, 1333, 1199 MHz pci0 at mainbus0 bus 0 pchb0 at pci0 dev 0 function 0 "Intel Core Host" rev 0x02 inteldrm0 at pci0 dev 2 function 0 "Intel HD Graphics" rev 0x02 drm0 at inteldrm0 intagp0 at inteldrm0 agp0 at intagp0: aperture at 0xd0000000, size 0x10000000 inteldrm0: msi inteldrm0: 1280x800 wsdisplay0 at inteldrm0 mux 1: console (std, vt100 emulation) wsdisplay0: screen 1-5 added (std, vt100 emulation) "Intel 3400 MEI" rev 0x06 at pci0 dev 22 function 0 not configured puc0 at pci0 dev 22 function 3 "Intel 3400 KT" rev 0x06: ports: 1 com com4 at puc0 port 0 apic 1 int 17: ns16550a, 16 byte fifo com4: probed fifo depth: 0 bytes em0 at pci0 dev 25 function 0 "Intel 82577LM" rev 0x06: msi, address f0:de:f1:31:ca:8d ehci0 at pci0 dev 26 function 0 "Intel 3400 USB" rev 0x06: apic 1 int 23 usb0 at ehci0: USB revision 2.0 uhub0 at usb0 "Intel EHCI root hub" rev 2.00/1.00 addr 1 azalia0 at pci0 dev 27 function 0 "Intel 3400 HD Audio" rev 0x06: msi azalia0: codecs: Conexant/0x5069, Intel/0x2804, using Conexant/0x5069 audio0 at azalia0 ppb0 at pci0 dev 28 function 0 "Intel 3400 PCIE" rev 0x06: msi pci1 at ppb0 bus 13 ppb1 at pci0 dev 28 function 3 "Intel 3400 PCIE" rev 0x06: msi pci2 at ppb1 bus 5 ppb2 at pci0 dev 28 function 4 "Intel 3400 PCIE" rev 0x06: msi pci3 at ppb2 bus 2 iwn0 at pci3 dev 0 function 0 "Intel Centrino Advanced-N 6200" rev 0x35: msi, MIMO 2T2R, MoW, address 58:94:6b:74:8d:c4 ehci1 at pci0 dev 29 function 0 "Intel 3400 USB" rev 0x06: apic 1 int 19 usb1 at ehci1: USB revision 2.0 uhub1 at usb1 "Intel EHCI root hub" rev 2.00/1.00 addr 1 ppb3 at pci0 dev 30 function 0 "Intel 82801BAM Hub-to-PCI" rev 0xa6 pci4 at ppb3 bus 14 pcib0 at pci0 dev 31 function 0 "Intel QM57 LPC" rev 0x06 ahci0 at pci0 dev 31 function 2 "Intel 3400 AHCI" rev 0x06: msi, AHCI 1.3 ahci0: port 0: 3.0Gb/s scsibus1 at ahci0: 32 targets sd0 at scsibus1 targ 0 lun 0: <ATA, Patriot Blast, SAFM> SCSI3 0/direct fixed t10.ATA_Patriot_Blast_8E3107590B0802607414 sd0: 228936MB, 512 bytes/sector, 468862128 sectors, thin ichiic0 at pci0 dev 31 function 3 "Intel 3400 SMBus" rev 0x06: apic 1 int 23 iic0 at ichiic0 spdmem0 at iic0 addr 0x50: 2GB DDR3 SDRAM PC3-10600 SO-DIMM spdmem1 at iic0 addr 0x51: 2GB DDR3 SDRAM PC3-10600 SO-DIMM itherm0 at pci0 dev 31 function 6 "Intel 3400 Thermal" rev 0x06 isa0 at pcib0 isadma0 at isa0 pckbc0 at isa0 port 0x60/5 irq 1 irq 12 pckbd0 at pckbc0 (kbd slot) wskbd0 at pckbd0: console keyboard, using wsdisplay0 pms0 at pckbc0 (aux slot) wsmouse0 at pms0 mux 0 wsmouse1 at pms0 mux 0 pms0: Synaptics touchpad, firmware 7.4 pcppi0 at isa0 port 0x61 spkr0 at pcppi0 aps0 at isa0 port 0x1600/31 pci5 at mainbus0 bus 255 pchb1 at pci5 dev 0 function 0 "Intel QuickPath" rev 0x02 pchb2 at pci5 dev 0 function 1 "Intel QuickPath" rev 0x02 pchb3 at pci5 dev 2 function 0 "Intel QPI Link" rev 0x02 pchb4 at pci5 dev 2 function 1 "Intel QPI Physical" rev 0x02 pchb5 at pci5 dev 2 function 2 "Intel Reserved" rev 0x02 pchb6 at pci5 dev 2 function 3 "Intel Reserved" rev 0x02 uhub2 at uhub0 port 1 "Intel Rate Matching Hub" rev 2.00/0.00 addr 2 uhidev0 at uhub2 port 1 configuration 1 interface 0 "Yubico Yubikey NEO OTP+U2F" rev 2.00/3.43 addr 3 uhidev0: iclass 3/1 ukbd0 at uhidev0: 8 variable keys, 6 key codes wskbd1 at ukbd0 mux 1 wskbd1: connecting to wsdisplay0 uhidev1 at uhub2 port 1 configuration 1 interface 1 "Yubico Yubikey NEO OTP+U2F" rev 2.00/3.43 addr 3 uhidev1: iclass 3/0 uhid0 at uhidev1: input=64, output=64, feature=0 ugen0 at uhub2 port 3 "UPEK Biometric Coprocessor" rev 1.01/0.02 addr 4 ugen1 at uhub2 port 4 "Broadcom Corp Broadcom Bluetooth Device" rev 2.00/3.60 addr 5 uvideo0 at uhub2 port 6 configuration 1 interface 0 "Chicony Electronics Co., Ltd. Integrated Camera" rev 2.00/23.45 addr 6 video0 at uvideo0 uhub3 at uhub1 port 1 "Intel Rate Matching Hub" rev 2.00/0.00 addr 2 umass0 at uhub3 port 1 configuration 1 interface 0 "Generic USB2.0-CRW" rev 2.00/58.88 addr 3 umass0: using SCSI over Bulk-Only scsibus2 at umass0: 2 targets, initiator 0 sd1 at scsibus2 targ 1 lun 0: <Generic-, Multi-Card, 1.00> SCSI0 0/direct removable serial.0bda0159114173400000 sd1: 29476MB, 512 bytes/sector, 60367872 sectors vscsi0 at root scsibus3 at vscsi0: 256 targets softraid0 at root scsibus4 at softraid0: 256 targets root on sd0a (419e46d9d4b3823f.a) swap on sd0b dump on sd0b